Employee Benefit Plans and Other Postretirement Benefits (Schedule Of Fair Value Of Pension Plan and Postretirement Healthcare Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	$ 2,162,885	$ 1,899,889
Total assets in the fair value hierarchy excluding assets measured at net asset value	2,148,684	1,877,945
Pension Plan Assets | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	1,368,474	1,127,105
Pension Plan Assets | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	780,210	750,840
Pension Plan Assets | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	51,082	84,548
Pension Plan Assets | Cash and cash equivalents | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	1,057	1,284
Pension Plan Assets | Cash and cash equivalents | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	50,025	83,264
Pension Plan Assets | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	1,283,092	1,044,455
Pension Plan Assets | Equity Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	1,265,676	1,027,189
Pension Plan Assets | Equity Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	17,416	17,266
Pension Plan Assets | U.S. companies
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	722,527	603,568
Pension Plan Assets | U.S. companies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	705,111	586,302
Pension Plan Assets | U.S. companies | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	17,416	17,266
Pension Plan Assets | Foreign companies
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	78,765	50,256
Pension Plan Assets | Foreign companies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	78,765	50,256
Pension Plan Assets | Foreign companies | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Pension Plan Assets | Harley-Davidson common stock
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	64,800	74,301
Pension Plan Assets | Harley-Davidson common stock | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	64,800	74,301
Pension Plan Assets | Harley-Davidson common stock | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Pension Plan Assets | Pooled equity funds
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	416,881	316,225
Pension Plan Assets | Pooled equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	416,881	316,225
Pension Plan Assets | Pooled equity funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Pension Plan Assets | Other
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	119	105
Pension Plan Assets | Other | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	119	105
Pension Plan Assets | Other | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Pension Plan Assets | Fixed-income holdings
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	814,510	748,942
Pension Plan Assets | Fixed-income holdings | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	101,741	98,632
Pension Plan Assets | Fixed-income holdings | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	712,769	650,310
Pension Plan Assets | U.S. Treasuries
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	39,866	41,089
Pension Plan Assets | U.S. Treasuries | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	39,866	41,089
Pension Plan Assets | U.S. Treasuries | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Pension Plan Assets | Federal agencies
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	29,188	36,210
Pension Plan Assets | Federal agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Pension Plan Assets | Federal agencies | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	29,188	36,210
Pension Plan Assets | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	462,563	418,522
Pension Plan Assets | Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Pension Plan Assets | Corporate bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	462,563	418,522
Pension Plan Assets | Pooled fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	189,361	170,741
Pension Plan Assets | Pooled fixed income funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	61,875	57,543
Pension Plan Assets | Pooled fixed income funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	127,486	113,198
Pension Plan Assets | Foreign bonds
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	81,732	69,871
Pension Plan Assets | Foreign bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Pension Plan Assets | Foreign bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	81,732	69,871
Pension Plan Assets | Municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	11,800	12,509
Pension Plan Assets | Municipal bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Pension Plan Assets | Municipal bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	11,800	12,509
Pension Plan Assets | Limited partnership interests
Defined Benefit Plan Disclosure [Line Items]
Assets measured at net asset value	9,099	9,321
Pension Plan Assets | Real estate investment trust
Defined Benefit Plan Disclosure [Line Items]
Assets measured at net asset value	5,102	12,623
Postretirement Health Coverage
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	217,537	170,092	$ 156,765
Total assets in the fair value hierarchy excluding assets measured at net asset value	210,787	164,574
Postretirement Health Coverage | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	179,056	131,221
Postretirement Health Coverage | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	31,731	33,353
Postretirement Health Coverage | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	19,317	4,442
Postretirement Health Coverage | Cash and cash equivalents | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	1,180
Postretirement Health Coverage | Cash and cash equivalents | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	19,317	3,262
Postretirement Health Coverage | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	144,795	117,974
Postretirement Health Coverage | Equity Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	144,792	117,779
Postretirement Health Coverage | Equity Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	3	195
Postretirement Health Coverage | U.S. companies
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	101,720	84,643
Postretirement Health Coverage | U.S. companies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	101,720	84,643
Postretirement Health Coverage | U.S. companies | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Postretirement Health Coverage | Foreign companies
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	19,498	14,190
Postretirement Health Coverage | Foreign companies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	19,495	13,995
Postretirement Health Coverage | Foreign companies | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	3	195
Postretirement Health Coverage | Pooled equity funds
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	23,563	19,132
Postretirement Health Coverage | Pooled equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	23,563	19,132
Postretirement Health Coverage | Pooled equity funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Postretirement Health Coverage | Other
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	14	9
Postretirement Health Coverage | Other | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	14	9
Postretirement Health Coverage | Other | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Postretirement Health Coverage | Fixed-income holdings
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	46,675	42,158
Postretirement Health Coverage | Fixed-income holdings | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	34,264	12,262
Postretirement Health Coverage | Fixed-income holdings | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	12,411	29,896
Postretirement Health Coverage | U.S. Treasuries
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	6,803	12,262
Postretirement Health Coverage | U.S. Treasuries | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	6,803	12,262
Postretirement Health Coverage | U.S. Treasuries | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Postretirement Health Coverage | Federal agencies
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	5,060	7,364
Postretirement Health Coverage | Federal agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Postretirement Health Coverage | Federal agencies | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	5,060	7,364
Postretirement Health Coverage | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	6,756	11,750
Postretirement Health Coverage | Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Postretirement Health Coverage | Corporate bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	6,756	11,750
Postretirement Health Coverage | Pooled fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	27,461	9,690
Postretirement Health Coverage | Pooled fixed income funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	27,461	0
Postretirement Health Coverage | Pooled fixed income funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	9,690
Postretirement Health Coverage | Foreign bonds
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	311	633
Postretirement Health Coverage | Foreign bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Postretirement Health Coverage | Foreign bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	311	633
Postretirement Health Coverage | Municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	284	459
Postretirement Health Coverage | Municipal bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Postretirement Health Coverage | Municipal bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	284	459
Postretirement Health Coverage | Real estate investment trust
Defined Benefit Plan Disclosure [Line Items]
Assets measured at net asset value	$ 6,750	$ 5,518